How to Close Your Pool for the Season — 2026 Guide

By PoolBotLab Editors · Updated August 2026 · 12 min read

Summer is winding down. The water's still warm, the kids have been in it every day for three months, and the idea of spending another weekend on pool maintenance is getting harder to justify. But how you close your pool this fall is going to determine what you're dealing with when you open it next spring — and the difference between a good close and a careless one is measured in algae, staining, and chemistry bills.

This guide walks through every step in the right order, including one that most pool closing checklists underemphasize: the final robot clean. Done right, closing takes a day (or two short sessions), and you open in spring to water that's clear and a pool that needs minimal work. Done wrong, you're staring at a green swamp in April.

Step 1: Do a final deep clean before anything else

This is the step most pool owners rush or skip — and it's the one that causes the most problems come spring. Any debris, algae spores, biofilm, or organic material left on the pool floor, walls, or waterline will continue to break down slowly under the cover all winter. By April it's become staining, scale, and entrenched algae that take multiple treatments and days of work to clear.

Run your robot pool cleaner for a complete session — floor, walls, and waterline — before you add any winterizing chemicals. A thorough robot pass picks up the debris and biofilm that's built up over the season, so your winterizing chemicals go to work on the actual water rather than trying to compensate for surface contamination.

For this final-of-season clean, the Beatbot AquaSense 2 Pro is the most complete option: its 5-in-1 cleaning system covers the floor, walls, waterline, surface debris, and water clarification in a single session. Nothing is left untouched. The AIPER Scuba X1 Pro Max is an excellent choice at a lower price point — its high-suction 4-in-1 system is particularly effective at pulling debris off pool walls and out of corners before you shut down for the season. Even the Beatbot AquaSense 2 and Dolphin Nautilus CC Plus at lower price points will do an effective closing clean — the key is simply running the robot before touching the chemistry.

Step 2: Balance your water chemistry

Test your water before adding winterizing chemicals — you need to know what you're working with. Target ranges for pool closing:

Get pH and alkalinity within range before you do anything else. Shocking out-of-range water is less effective and wastes chemicals. Alkalinity first, then pH — they're connected, and adjusting alkalinity will shift pH.

Step 3: Shock the pool

After balancing chemistry, shock the pool with a heavy dose of chlorine — at minimum 2 lbs of calcium hypochlorite per 10,000 gallons of pool water. If you've had any algae issues during the season, double that. The goal is to raise free chlorine to 10–15 ppm and let the pool circulate overnight.

Shock at dusk or night — UV from the sun degrades chlorine quickly, and shocking after dark gives it time to work without being burned off before it can sanitize the water.

Step 4: Clean and backwash the filter

A dirty filter stored over winter is harder to clean in spring and degrades faster. Before closing:

• Sand filters: Backwash until the sight glass runs clear, then set the handle to the "Winter" position (between settings) if your filter has one.
• Cartridge filters: Remove the cartridge, rinse thoroughly with a garden hose, and let it dry completely. Store it indoors — cartridges left wet in cold temperatures can crack.
• DE filters: Backwash, then disassemble and hose off the grids. Inspect the grids for tears and replace any that are damaged before spring startup.

Remove the drain plug from your filter and pump housing and store it indoors so there's nothing to freeze and crack.

Step 5: Lower the water level

For pools in climates where temperatures regularly drop below freezing, lower the water level to 4–6 inches below the skimmer opening. Water left sitting in the skimmer will freeze, expand, and crack the skimmer body — a repair that runs several hundred dollars.

In warmer climates where hard freezes are rare, lowering the water level just below the return jets is sufficient. Check your winter cover manufacturer's guidelines — some mesh safety covers work better with the water closer to the normal level to support the cover against rain accumulation.

Use your pump to drain to the right level, or a submersible utility pump if you need to go lower quickly. Don't drain completely — you need enough water weight to prevent the pool shell from floating if there's high groundwater pressure in your area.

Step 6: Blow out and plug the lines (freeze climates)

This is the most technical step and the most important for freeze protection. Any water sitting in return lines, suction lines, or the pump/filter system will expand when it freezes and can crack pipes, fittings, and equipment — repairs that can run into the thousands.

Use a shop vac or air compressor to blow water out of each line from the equipment pad side, then immediately plug the return fittings and skimmer outlets underwater with expansion plugs (rubber plugs with a wing nut that expands to seal). Blow and plug each line individually — don't try to blow multiple lines at once.

Add non-toxic pool antifreeze (propylene glycol, not automotive antifreeze) to the skimmer line as a second layer of protection if your winters are particularly harsh. A gallon per skimmer is typical.

Step 7: Add algaecide and cover

Once chlorine levels have dropped back to 1–3 ppm (usually 24–48 hours after shocking), add a winterizing algaecide per the manufacturer's dosage for your pool volume. Brush the pool walls once more to help distribute the algaecide, run the pump for a few hours, then shut everything down.

Install your winter cover carefully. Safety covers (mesh or solid with anchors) are significantly better than the basic tarp-style covers at preventing debris intrusion and evaporation over winter. A quality cover is worth the investment if you're planning to maintain the pool long-term.

Weigh down or anchor the cover properly — a loose cover that allows debris underneath is almost as bad as no cover at all.

Storing your robot cleaner for winter

Your robot pool cleaner represents a significant investment — storing it correctly over winter protects that investment and ensures it's ready to perform when you open next season.

After the final cleaning session: rinse the robot thoroughly with a garden hose to remove any pool chemicals, clean the filter basket or cartridge completely, and allow the robot to dry fully in the sun before storage. Do not store a wet robot — moisture trapped in the internal components over months can cause corrosion and electrical issues.

For cordless models like the Beatbot AquaSense 2 Pro and the AIPER Scuba X1 Pro Max, battery storage matters. Lithium batteries stored at full charge or fully depleted for extended periods degrade faster. Store cordless robots at 40–60% charge if possible. Check the battery level once a month during storage and top up slightly if it drops below 20%.

Store robots indoors — in a garage, basement, or storage room — where temperatures stay above freezing. The swivel cable on corded models should be coiled loosely (not wound tightly) to prevent kinking. If your robot came with a storage caddy or cart, use it.

Best robot pool cleaners for end-of-season closing

If you're shopping for a robot to add to your closing routine (or upgrading before you button up for the season), here's where to focus:

Frequently asked questions